diff --git a/Lib/ntpath.py b/Lib/ntpath.py
index fa2fc29..c4a4ac5 100644
--- a/Lib/ntpath.py
+++ b/Lib/ntpath.py
@@ -490,4 +490,6 @@
         i += 1
 
     rel_list = [pardir] * (len(start_list)-i) + path_list[i:]
+    if not rel_list:
+        return curdir
     return join(*rel_list)